Research Concerning the Obtaining From Industrial Wastes of a Cover Powder Used in Steel Continuous Casting

Abstract:

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The paper presents research carried out in order to obtain thermo-isolating and covering
powder used in the Tundish of the continuous casting installations. This powder is made by using
different types of waste originating in the iron and steel industry and in the energy industry, such as:
thermal power-station ashes, furnace slag, B.C.A. scraps, limestone, black ash, fluorine, raw
dolomite, graphite powder. The powder thus obtained must have a faster melting speed and a lower
melting temperature; it does not make the steel impure or diminish the heat losses through radiation.
An effect of applying the experimental results in industry, besides financial economies, is to obtain
an accelerated integration of a technological process in companies, according to European Union
requirements regarding the preservation of the environment.

Abstract: Concrete properties can be greatly improved with the advanced mineral admixtures such as steel slag powder. Used in combination with Super-plasticizer admixture, steel slag powder can lead to economical high performance concrete with enhanced durability and reduced cement content. The effectiveness of steel slag powder on suppressing Alkali Aggregate Reaction is analyzed. The effectiveness of steel slag powder on suppressing AAR expansion was assessed using the method of ASTM C441 and accelerated test method. Results show that mineral admixtures with steel slag powder as partial replacement for Portland cement in concrete is an effective means for controlling expansion due to AAR. At most a 50% decrease in expansion rate of mortar bars can be found.

Abstract: The characteristic temperatures of the selected quaternary CaO-MgO-Al2O3-SiO2 slags have been measured by the hemisphere method. The effects of the basicity value and Al2O3 content studied. The results indicated that basicity and the Al2O3 content had obvious influence on the characteristic temperatures of the selected slags. All of the softening temperature, the hemisphere temperature and the flow temperature decrease with the increasing of the basicity value. Under the same content of CaO, the characteristic temperature decreased sharply by adding Al2O3. The solidus and liquidus temperatures computed from the FactSage database were compared with the present experimental observations as well as the melting temperature information of the DSC measurements. The results also indicated that it is possible to get a reasonable idea of the solidus temperature from the hemisphere temperature while the flow temperature would indicate the liquidus temperature.

Abstract: This present paper focuses on the viscosities of high titanium containing slags in the process of titanomagnetite smelting by taking the TiO2-Al2O3-CaO-SiO2 quaternary system as the object. Experimental determinations of the viscosities were carried out in the temperature range from 1573 to 1773K using the rotation cylinder method. The measurements were conducted in the composition range from 23 to 33 mass pct TiO2, 3 to 9 mass pct Al2O3, and 0.3 to 0.7 basicity (mass ratio of CaO to SiO2). The effects of TiO2, Al2O3, basicity, and temperature on viscosity were studied. The experimental results indicated that the viscosities decreased with increasing TiO2 content and basicity, and increased with increasing Al2O3 content, above the liquidus temperature. Based on the experimental data, the liquidus temperatures of the slags were evaluated using the second derivatives of the activation energies for viscous flow with respect to temperature.

Abstract: Liquidus temperature, electrical conductivity and phase composition of Al2O3-CaO-Na2CO3 slag were studied in the paper. The results showed that the minimum value of liquidus temperature was 1429°C when the content of Na2CO3 was 11%. The Al2O3-CaO-Na2CO3 slag of lower liquidus temperature had higher electrical conductivity, and the electrical conductivity of Al2O3-CaO-Na2CO3 slag increased with the increase of temperature. The main phases of Al2O3-CaO-Na2CO3 slag are composed of CaAl2O4, Ca3Al10O18, NaAlO2 and Na2CO3. The addition of Na2CO3 is to be more effective for decreasing liquidus temperature and increasing electrical conductivity in the Al2O3-CaO-Na2CO3 slag system.

Abstract: The variations of T[O] and [N] as well as non metallic inclusions in different working processes of two kinds of SS400 steel production process in Han Group are studied systematically by tracing experiment, systematic sampling and integrated analyzing. The following results are observed: slag washing process and traditional process can both produce qualified steel. The slag washing process has good removal effect for Al2O3 inclusion compared with the traditional process. After slag washing treatment，the content of T[O] and [N] in slab when steady-state casting are respectively 21.75×10-6 and 24.9×10-6, which are respectively 84.9% and 76.1% of the content after LF treatment. The number of the micro inclusions is 5.583 piece/mm2,which is 79.2% of the number after LF treatment.